A number of dental matrices for use in connection with filling cavities have been available for some time. Some of these matrices are specifically designed for fillings located in interproximal areas between adjacent teeth.
Normally, adjacent healthy teeth are in proximal contact with each other at a contact point. However, if a tooth experiences decay or otherwise experiences damage, its contact point with the adjacent tooth may be lost. During restoration of the tooth, therefore, it is important for a proper contact point with the adjacent tooth to be restored.
In removing decay and in restoring a decayed tooth, the dentist attempts to preserve as much natural tooth as possible and restore the tooth with a proper contact point. When posterior teeth have interproximal decay on mesial or distal surfaces, a dentist will use a hand piece to remove sufficient tooth structure to gain access to the decay, remove the decay and shape the resultant void in the tooth in preparation of filling the void. A matrix is placed interproximally and is typically wrapped around the sides of the tooth to define the desired shape of the finished tooth and to keep the filling material from flowing beyond the desired tooth boundary. A matrix typically comprises a thin metallic or plastic strip that is flexible and can be bent around the tooth being restored. A malleable filling is then placed and hardened, following which the matrix is removed.
A common problem in placing a matrix interproximally is that the tooth to be filled will often be in very tight contact with the adjacent tooth, and therefore it becomes difficult to place the matrix interproximally. This difficulty is especially pronounced when using sectional matrix strips that merely cover one interproximal wall of the affected tooth, as opposed to circumferential matrix bands that fit over and around the entire tooth somewhat more easily. Currently, dentists try to overcome this problem by cutting away additional tooth structure interproximally, thus widening the distance between the adjacent teeth so as to more easily place the matrix. However, cutting away healthy, irreplaceable tooth structure is undesirable since it is not minimally invasive.
Another method for overcoming this problem is to place a separating ring or wedge interproximally before beginning to remove the decay; in that way, by the time the preparation of the cavity is complete, a separation has been created between the adjacent teeth, so that it is now easy to place the matrix interproximally. The problem with this technique, however, is that the pre-operative presence of the ring or wedge limits visibility and accessibility for the dentist. Moreover, the separating ring or wedge must also be removed during the placement of a matrix and then replaced during the filling of a cavity causing the dentist to perform an extra step in the process.
For aiding the filling of an area located interproximally between adjacent teeth, one matrix is disclosed in U.S. Pat. No. 2,039,419 dated Jun. 11, 1934, to Hutchinson. The matrix includes a piece of sheet metal with two wire tie members. A piece of dental floss is hooked to one of the wire members so that the matrix may be inserted interproximally by first dragging the floss through the space between the adjacent teeth.
Despite its ostensible utility, this matrix suffers from a number of deficiencies. For example, the matrix does not effectively loosen the tight space between the adjacent teeth for entry of the matrix since the depth of the matrix is comprised of both the sheet metal and wire ligature. In practice, such a matrix is actually more difficult to pass through the space between the teeth since the sheet metal and wire ligature must pass through the space at once.
U.S. Pat. No. 6,712,608, to Bills, for anatomically contoured matrix bands for use in dental restoration procedures, discloses a matrix band having an asymmetrical shape to provide form for molding a dental filling into a shape that closely approximates the asymmetrical and generally trapezoidal shape of a tooth. However, this matrix is difficult to place interproximally and is used in conjunction with a separating ring during the preparation of the cavity. As mentioned above, these separating rings often cause the cavity area to be less visible and accessible to the dentist.
The prior art does not provide for a dental matrix which is easily inserted interproximally. Current matrices are difficult to insert between tight contact points. That is, prior art applications, including those referenced above, have in general provided a matrix that is bulky and difficult to insert without either cutting away additional, irreplaceable tooth structure or by first utilizing a separating ring or wedge in order to facilitate inserting the matrix between the adjacent teeth.
Thus, as is clear from the prior art, a definitive need exists for a dental matrix which may be easily inserted between adjacent teeth and which provides the proper contour for filling the cavity.